This invention relates generally to electrophotographic printing, and more particularly, concerns increasing the capacity of the cleaner sump.
One of the constraints on the life of a Customer Replaceable Unit (CRU) is the capacity of the cleaner sump. This constraint is especially true for small copiers or printers which must avoid toner transportation devices that limit the sump capacity to that of the volume that can be reached by gravity assisted flow alone. Once all the gravity assisted flow assessable volume is filled, the pressure on the cleaning blade and on the sealing Mylar flap (i.e. the flap prevents waste toner from leaking from the sump) starts building up resulting in a cleaner failure. The cleaner failure is either a toner spill through a lower seal or failure to clean adequately. The CRU life can be extended by utilizing more of the available sump capacity that is not filled by gravity assisted flow alone, to prolong the cleaner failures occurring due to pressure on the cleaning blade and flap.
The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 4,547,063 to Stange discloses a moving magnet cleaner for scraping excess toner off of a photoreceptor surface. The moving magnet cleaner provides carrier bristles for brushing the photoreceptor surface. The sweeping of the moving magnet cleaner past the photoreceptor provides a self-leveling of the carrier bristles to the size of the distance between the cleaner roll and the photoreceptor surface. A toner roll rotates in proximity to the cleaner roll to transfer toner from the carrier particles to the toner roll and also provides self-leveling of the carrier bristles. The carrier for the magnet cleaner is continually replaced with carrier from a sump and the moving magnet cleaner exhibits a large cleaning zone allowing for gentle removal of the toner from the photoreceptor.
U.S. Pat. No. 4,671,207 to Hilbert discloses a magnetic brush development apparatus for applying developer material to a latent image on a photoconductor which includes a housing having a sump which receives a supply of developer material. A magnetic brush spaced from the sump applies the material to the latent image of a photoconductor as a photoconductor is moved past a magnetic brush. A feed mechanism delivers developer material from the sump through a slot to the magnetic brush. The feed mechanism includes a rotatable shell and a plurality of magnets that are located within the shell and attract developer material to a portion of the shell. The shell has a deeply fluted outer surface that holds the developer material attracted to the shell as it is delivered from the sump to the slot.
U.S. Pat. No. 5,080,038 to Rubin discloses a development apparatus for developing latent images on an image-bearing surface which includes a magnetic core generating a first magnetic field, a non-magnetic shell, surrounding and spaced from the magnetic core, and a transport assist magnet mounted at a desired spot between the non-magneticshell and the magnetic core. The transport assist magnet generates a second magnetic field at and about the desired spot thereby creating a magnetic field strength gradient thereabout for assisting the magnetic transportation of magnetic developer material over the surface of the non-magnetic shell.
U.S. Pat. No. 5,111,247 to Nichols discloses a toner concentration sensing system for controlling the dispensing of toner into a developer sump. A toner concentration sensor is located in the bottom of the mixing area of the developer sump adjacent one of the mixing augers. A magnet is positioned on the rotating mixing auger for rotating with the auger past the toner concentration sensor. As the auger rotates, the magnet with developer material adhering thereto, sweeps the top of the toner sensor to improve the accuracy of the toner concentration readings.